SARS-CoV-2 Seroprevalence in Healthcare Workers before the Vaccination in Poland: Evolution from the First to the Second Pandemic Outbreak

Abstract

Healthcare workers (HCWs) are on the frontline, struggling with the pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To describe recent or past infections, the serological assays enabled the assessment of the immune response developed in coronavirus disease (COVID-19) in the period when testing was hardly available. In this study, we investigated SARS-CoV-2 seroprevalence in HCWs in a Polish teaching hospital and the Regional Occupational Medicine Center after both the first and the second waves. ELISA-based tests for anti-SARS-CoV-2 IgA and IgG were used to determine immune response to SARS-CoV-2 in volunteer HCWs who worked in those institutions in May 2020 (208 participants aged 47.1 ± 12.5, 88% women) and in December 2020 (179 participants aged 45.2 ± 12.4, 86% woman). Risk factors for seropositivity were also assessed using a questionnaire filled out by all participants. We reported a significant increase in seroprevalence after the second wave (22.9%) compared with the first outbreak (2.4%) (OR 12.1; 95%CI 4.6–31.3; p < 0.0001). An association between IgG seroprevalence and severity of infections was noted. Furthermore, we demonstrated that amongst medical personnel, nurses exhibited a proportionally higher SARS-CoV-2 seroprevalence. Moreover, given the high seroprevalence in non-clinical group of HCWs, we suggest that community transmission can play a superior role to workplace exposure.

The Longitudinal Analysis on the Anti-SARS-CoV-2 Antibodies among Healthcare Workers in Poland—Before and after BNT126b2 mRNA COVID-19 Vaccination

“…After the second wave of the pandemic, i.e., November 2020–January 2021, which led to 1.4 million confirmed COVID-19 cases and 33.4 thousand COVID-19-related deaths [ 15 ], we observed a significant increase in seroprevalence among enrolled HCWs. A similar observation was made among HCWs from different Polish cities, e.g., Lublin [ 22 ]; however, this seroprevalence was two times lower. These discrepancies can be explained by the differences in the number of confirmed COVID-19 cases at the end of the second wave of the pandemic in the Greater Poland and Lublin regions, 132,423 and 66,027, respectively [ 15 ].…”

“…However, we did not identify any HCWs with anti-SARS-CoV-2 antibodies after the first wave, i.e., May–September 2020. Very low seroprevalence among medical personnel at the same time was also noted in different Polish cities, i.e., Warsaw 0.85% [ 20 ], Opole 1.1% [ 21 ], and Lublin 2.4% [ 22 ], and low numbers of COVID-19 cases among HCWs after the first months of the pandemic were found in different countries, i.e., Germany 1.6% [ 24 ], Greece 1.3% [ 25 ], and the USA 1.1% [ 26 , 27 ]. This can be explained by low seroprevalence in the general population after the first wave of the pandemic, i.e., the Greater Poland region 0.97% [ 4 ], Greece 0.36% [ 28 ], and the USA 1% [ 29 , 30 ].…”

“…However, it should be highlighted that vaccine protection is not endless and a reduction in effectiveness against COVID-19 and waning immunity with time was observed [ 19 ]. The seroprevalence of SARS-CoV-2 infection, as well as antibody response after COVID-19 vaccination among HCWs in Poland [ 20 , 21 , 22 ], as well as other countries [ 3 , 23 , 24 ] were analyzed by many research groups. The immune response to natural SARS-CoV-2 infection, as well as COVID-19 vaccination, is not fully understood.…”

Non-Pharmacological Preventive Measures Had an Impact on COVID-19 in Healthcare Workers before the Vaccination Effect: A Cohort Study

“…This higher community incidence, contrasting with the lower incidence among healthcare workers, further underlines the important role played by non-pharmaceutical preventive measures at PSMar. Moreover, the opposite trend is observed in similar hospitals in Poland [ 24 ] and Germany [ 25 ], which show a significant increase in the incidence among healthcare workers, concluding that their preventive strategy should be improved. However, it should also be noted that the lower number of admissions of patients with COVID-19 in the second period compared to the first may have also contributed to the lower incidence of cases among healthcare workers.…”

A prevalence study of COVID-19 among healthcare workers in a pandemic hospital in the Samsun province of Turkey

“…In the Netherlands a report noted a seroprevalence increase from 4.1% to 13.8% in a paediatric population when sampling during the first or second waves of infection in 2020 [ 36 ]. In a cohort of healthcare worker in Belgium, seroprevalence increased by 29.4% (12.4% to 41.8%) while in a healthcare population in Poland seroprevalence increased from 2.4% to 22.9% from one wave to the next in 2020 [ 37 , 38 ].…”